Final answer:
Disgruntled engineers not approving a contract signifies that they rejected it. The correct answer to the question is option b) Rejected.
Step-by-step explanation:
When it is said that the disgruntled engineers in the union voted not to approve the contract, it means they rejected the contract. The term disgruntled suggests dissatisfaction or displeasure, indicating that the engineers were unhappy with the terms proposed in the contract. Given the context of the question, the correct answer would be option b) Rejected.